An end-fed half-wave antenna is a type of radio antenna that is used for transmitting and receiving electromagnetic waves. It is called "end-fed" because one end of the antenna is connected to the transmission line or the feed line, while the other end is left open or connected to a ground plane.
The term "half-wave" refers to the length of the antenna, which is approximately half the wavelength of the desired frequency of operation. For example, if you want to operate the antenna at a frequency of 100 MHz, the length of the antenna would be around 1.5 meters, which is half the wavelength of 100 MHz electromagnetic waves in free space.
The end-fed half-wave antenna typically consists of a long wire or a conductor that is resonant at the desired frequency. It can be oriented vertically, horizontally, or at an angle, depending on the specific application. The feed line is connected to one end of the antenna, and the other end is left unconnected or connected to a ground plane.
One of the advantages of an end-fed half-wave antenna is its simplicity and ease of installation. It requires a single connection to the feed line, making it convenient for portable or temporary setups. Additionally, it can be used across a wide range of frequencies by using an antenna tuner to match the impedance of the antenna to the transmission line.
However, end-fed half-wave antennas can be more challenging to match to the transmission line compared to other types of antennas. They can exhibit higher impedance, which may require additional matching components to achieve efficient power transfer. Additionally, their radiation pattern and polarization characteristics can be influenced by nearby structures and the ground plane, which can affect their performance.
Overall, the end-fed half-wave antenna is a versatile option that can provide reasonable performance in various applications, including amateur radio, shortwave broadcasting, and wireless communication.